The present invention relates to a carbon fiber, an electrode material for a battery, and a method of manufacturing the carbon fiber.
A vapor-grown carbon fiber is known in the art.
This carbon fiber is a short fiber in which carbon obtained by pyrolysis of hydrocarbons such as benzene or methane at a temperature of about 700° C. to 1000° C. is grown with a catalyst particle such as an ultra-fine iron particle or nickel as a nucleus.
Carbon fibers generally have a structure in which the hexagonal carbon layers are grown concentrically or a structure in which the hexagonal carbon layers are grown in the axial direction. However, depending upon the vapor growth conditions such as catalyst, temperature range, and flow rate, carbon fibers may have a herring-bone structure in which the stacked hexagonal carbon layers are tilted with respect to the fiber axis at a specific angle.
Carbon fibers are often mixed with resins or the like and used as composites. However, carbon fibers generally have poor adhesion to resins.
This is because carbon fibers have a lower degree of surface activity since the hexagonal carbon layers (AB planes) are exposed on the inner and outer surfaces. Moreover, a thin deposited layer in which an excess amount of insufficiently crystallized amorphous carbon is deposited is inevitably formed on the surface of carbon fibers manufactured using a vapor growth process. This deposited layer also has a lower degree of activity, thereby resulting in poor adhesion to the resins.